The Cramér-Rao bound provides a limit on how the estimation can be performed. It sets a fundamental limit on the variance of the estimator \(\hat{\theta }\)  regardless of how it is constructed. It is expressed by the following formula [1]}, [2]}
\({\rm Var}\left(\hat{\theta }\right)\ge \frac{1}{n{\cal F}\left(\theta \right)},\) 
